The present invention relates to an all-digital and adjustable scale device, especially to an all-digital and adjustable scale device with a controller and a keyboard whereby user can input command through the keyboard for four-corner balance, adjustment, calibration and self-testing.
The conventional multiple load cell scale device, as shown in FIG. 1, comprises a controller 70, a connection box 65 containing a plurality of voltage regulators VR (VR 1-VR N) each connected to a corresponding load cell 60 on one end thereof. The another ends of the voltage regulators VR are tied together and connected to input of an A/D converter 701 within the controller 70. The output of the A/D converter 701 is connected to a microcomputer 702. The microcomputer 702 is connected to a keyboard 703, a display 704 and an interface 705 such as RS-232 interface.
The above-mentioned multiple load cell scale device should be adjusted through respective voltage regulators VR such that each load cell has signal with equivalent strength. The four comers of a loadometer using multiple load cell scale device have balance and the load measured at various points of a conveying surface is correct. However, for balance adjustment, the load of the above-mentioned multiple load cell scale device should be repeatedly loaded and unloaded, and the voltage regulators VR corresponding load cell also requires adjustment to obtain required accuracy within allowable error. The adjustment task requires experienced technician and each load cell should be of same specification. The adjustment task is influenced by human factor and the resolution is limited by the number of the load cell. The signal is degraded when the number of parallel-connected load cells is increased.
It is the object of the present invention to provide an all-digital and adjustable scale device, which does not need tool for adjustment, load cell of the same specification, and repeated loading and unloading of the load cell.
To achieve above object, the present invention provides an all-digital and adjustable scale device, which has a plurality of A/D converters to convert analog measurement result to digital value and a single-chip microcomputer to manipulate the digital value. The user can input command through a keyboard for four-corner balance, adjustment, calibration and self-testing.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: